Heat transfer apparatus



April 12, 1955 Filed Nov. 6, 1951 J. F. YOUNG HEAT TRANSFER APPARATUS 2 Sheets-Sheet l \nven-tor": James 11 Young,

5 H is Attorneg.

Aprll 12, 1955 J. F. YOUNG 2,706,105

HEAT TRANSFER APPARATUS Filed Nov. 6, 1951 2 Sheets-Sheet 2 James F. Young,

His Attovn normally effected by employing a condenser.

United States Patent HEAT TRANSFER APPARATUS James F. Young, Erie, Pa., assignor to General Electric Company, a corporation of New York Application November 6, 1951, Serial No. 255,121

Claims. (Cl. 257-36) My invention relates to heat transfer apparatus and more particularly to heat transfer apparatus employed in refrigerating systems.

It is necessary in many devices to provide apparatus for effecting transfer or dissipation of heat. By way of example, in refrigerating systems, it is necessary to dissipate heat from the compressed refrigerant, and this is A condenser employed for this purpose may be of the type described and claimed in the copending application of Ralph E. King, Serial No. 247,845, filed September 22, 1951, and assigned to the assignee of the present invention. As disclosed in the King application, improved heat transfer from apparatus of the type therein described and claimed can be secured by inclining the plane of the condenser with respect to a vertical plane, or more specifically with respect to the rear wall of the refrigerator upon which the condenser is mounted. As refrigerators are normally employed in the average kitchen the space between the rear wall of the refrigerator and the wall of the kitchen is limited, approximately 3" being so available. Accordingly, a condenser in which the passes of tubing and the heat dissipating wires are arranged in one plane may, because of the necessary size of the condenser required for dissipating of the proper amount of heat, be inclined only say 6 with respect to the vertical in the space available. A greater inclination toward the horizontal would be effective to produce still further improved heat transfer characteristics. By my invention a greater inclination of the condenser with respect to the vertical is made possible within the space limitations existing.

It is an object of my invention to provide an improved heat transfer apparatus having a high rate of heat dissipation.

It is another object of my invention to provide an improved heat transfer apparatus arranged to secure a more satisfactory flow of air thereover.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In carrying out the objects of my invention, a heat transfer apparatus or condenser is formed from a continuous serpentine conduit, providing a plurality of parallel passes, and a plurality of spaced wires secured to this conduit. Improved heat dissipation is achieved by forming the condenser to include at least two planar sections, as distinguished from a single planar section of the prior art condensers, the sections being inclined with respect to each other to secure a greater angle of inclination of each of the sections within the space limitations existing than is possible with a single section.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig. l is a side elevation view of a refrigerator incorporating an embodiment of my invention; Fig. 2 is an elevation view of the heat transfer apparatus taken along the line 2--2 in Fig. 1; Fig. 3 is an enlarged sectional elevation view taken along the line 33 of Fig. 2, and Figs. 4 and 5 are graphs showing the relationship between B. t. u. per hour of heat transferred and certain condenser characteristics.

Referring to Fig. 1, there is shown a refrigerator including a cabinet 1 having a vertical rear wall 2. The refrigerator is cooled by a refrigerating apparatus including a heat transfer apparatus or condenser 3. The heat transfer apparatus 3 is mounted on the rear wall 2 of the refrigerator by a plurality of brackets 4, 5 and 6, each of which includes loops 7 for engaging portions of the heat transfer apparatus 3. The brackets 4, 5 and 6 are secured to the rear wall 2 of the cabinet by screws or other suitable fastening devices passing through slots or openings 8 in the brackets.

Referring to Figs. 2 and 3, the heat transfer apparatus comprises a continuous conduit 9 arranged in serpentine form to provide a plurality of parallel passes 10. In the specific form illustrated, these parallel passes 10 are arranged to extend horizontally. In the application of this heat transfer apparatus to a household refrigerator, for example, compressed refrigerant is circulated through the conduit 9 and the passes 10 thereof for dissipating heat from the refrigerant. In order to facilitate the dissipation of heat from the refrigerant, a plurality of wires 11 are secured to the conduit 9 in spaced relationship to each other. These wires extend transversely of the passes 10 of the conduit 9 and are secured to the wall of the conduit in any suitable manner, as by welding or brazing. The wires 11 are arranged parallel to each other in spaced relationship along the length of the passes 10 of the conduit 9. In the structure illustrated, the wires 11 are arranged on both sides of the passes 10 of the conduit, as shown more clearly in Fig. 3.

It has been found that arranging such a condenser at an angle to the vertical in applications where upward convection of air by natural draft is relied upon for removing heat from the heat transfer apparatus has the effect of improving the heat dissipating capacity of the heat transfer apparatus. However, where such heat transfer apparatus is employed with household refrigerators, for example, the distance between the rear wall 2 and the wall of the kitchen or other room in which the refrigerator is placed is limited, being in the neighborhood of say 3". Since the width of the heat transfer apparatus or condenser is limited by the width of the refrigerator or the like upon which it is mounted, the height must be sufficient to provide an adequate heatdissipating surface. With the height required for the usual refrigerator and with the limited space available between the rear wall of the refrigerator and the wall of the room, the amount that the plane of the condenser can be inclined relative to a vertical plane and hence relative to the vertical rear wall of the refrigerator is limited to say about 6. A greater inclination of such a condenser with respect to the vertical would result in a greater air flow thereover, in better contact between the air and the condenser, and in the flow of air of a generally lower temperature and better heat dissiptaing capacity over the heat transfer apparatus. By my invention, the heat transfer apparatus is so formed as to provide a greater inclination of the portions thereof relative to the vertical within the limited space available.

To accomplish this purpose, the wires 11 are bent along horizontal lines extending through the points 12 so that the plane of an upper section 13 of the assembly comprising the heat transfer apparatus is inclined relative to a vertical plane and relative to the rear wall 2 of the cabinet. This planar section of the assembly is also inclined relative to a generally vertical central planar section 14 of the heat transfer apparatus which is spaced from the rear wall 2 by the maximum distance permissible under the existing space limitations. Similarly, the wires 11 are bent along lines extending through the points 15 so that a lower planar section 16 of the heat transfer apparatus is inclined with respect to a vertical plane and with respect to the vertical rear wall 2 of the cabinet. relative to the central vertical section 14 of the heat transfer apparatus. The central vertical section 14 is included primarily for securing a desired appearance of the overall heat transfer apparatus and from a heat transfer standpoint the heat transfer apparatus could be bent at the middle to provide only upper and lower sections. It can be seen that the upper and lower sections, 13 and 16 respectively, of the heat transfer apparatus are inclined at a substantially greater angle with respect to the vertical than would be possible were the This section 16 is, of course, also inclined entire heat transfer apparatus to be formed in a single plane. Because of this greater inclination of the sections 13 and 16, a greater heat dissipation is achieved from a condenser assembly arranged in the manner described above. In the arrangement illustrated, the passes of the conduit 9 extend horizontally and the transverse wires 11 are arranged to extend generally vertically. If desired, the heat transfer apparatus can be formed so that the passes 10 extend vertically and the transverse wires extend horizontally. In this latter case, of course, the bends corresponding to bends 12 and 15 would necessarily be made in the passes 10 of the conduit rather than in the wires. Also, while a heat transfer apparatus including two inclined sections has been shown and described, it will be apparent that a heat transfer apparatus including three or more such inclined sections could be employed, if desired.

Experimental results indicating the improvement obtained with heat transfer apparatus constructed in accordance with my invention are illustrated in the graphs of Figs. 4 and 5. In Fi 4, the heat transferred in B. t. u. per hour at 40 F. difference in temperature between the condenser and room air is plotted against the number of inclined planar sections of the condenser. It can be seen that when a single-plane condenser inclined at the maximum angle of approximately 6 was employed under the conditions set forth, the heat transferred is approximately 490 B. t. u. per hour. On the other hand, when a condenser including two inclined sections, as described above, was employed, the heat transferred rose to 590 B. t. u. per hour, an increase of over With a given condenser tube size, wire size and spacing of wires, the factors affecting the improvement to be obtained by using multiple inclined planar sections are the heat transfer conductance per pass (which increases with angles more nearly horizontal) and the pressure drop per pass (which increases in integer steps with more nearly horizontal angles, since the additional passes cause more resistance to flow of air). By taking into consideration these two factors, one of which tends to improve theheat transfer as the number of inclined sections is increased and the other of which tends to reduce the heat transfer under these conditions, the optimum number of inclined sections under particular conditions can be determined.

By reference to Fig. 4, it can be seen that, under the conditions there involved and with the size condenser required, the greatest heat transfer is secured with the use of a condenser including two inclined sections. When three inclined sections were employed, each inclined at the maximum angle permitted by the normal spacing between the rear wall of the refrigerator and the wall of the room in which it is used, the amount of heat transferred was 560 B. t. u. per hour, a decrease of 30 B. t. u. per hour from the maximum of 590 B. t. u. per hour secured with the condenser of two inclined sections.

In Fig. 5 the heat transfer in B. t. u. per hour is plotted against the average temperature difference between the condenser tubing and the room air for condensers including one, two and three inclined sections. It can be seen from Fig. 5 that the smallest amount of heat transfer throughout the entire range of temperature difference between condenser and room air plotted in Fig. 5 is secured when a condenser of the single-plane type is employed. The greatest heat transfer is again achieved when a condenser including two inclined sections is used and intermediate results are secured with the condenser including three inclined sections.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and described and I intend by the appended claims to cover all-modifications Within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A refrigerator comprising a cabinet including a vertical rear wall, a heat transfer apparatus forming an element of said refrigerator, said apparatus comprising a continuous serpentine conduit formed to provide a plurality of parallel passes, a plurality of spaced parallel wires secured to said conduit and extending transversely of said passes, and means for mounting said heat transfer apparatus on said rear wall, said heat transfer apparatus being formed to provide at least two connected planar sections each inclined relative to said rear wall, one of said sections being disposed vertically above the other section.

2. A refrigerator comprising a cabinet including a vertical rear wall, a heat transfer apparatus forming an element of said refrigerator, said apparatus comprising a continuous serpentine conduit formed to provide a plurality of parallel horizontal passes, a plurality of spaced parallel wires secured to said conduit and extending generally vertically transversely of said passes and means for mounting said heat transfer apparatus on said rear wall, said heat transfer apparatus being formed to provide at least two connected planar sections each inclined relative to said rear wall, one of said sections being disposed vertically above the other section.

3. A refrigerator comprising a cabinet including a vertical rear wall, a heat transfer apparatus forming an element of said refrigerator, said apparatus comprising a continuous serpentine conduit formed to provide a plurality of parallel horizontal passes, a plurality of spaced parallel wires secured to said conduit and extending generally vertically transversely of said passes, and means for mounting said heat transfer apparatus on said rear wall, said wires and said conduit being bent at points located in a horizontal plane extending between two adjacent passes to provide connected planar sections each inclined relative to said rear wall.

4. A refrigerator comprising a cabinet including a vertical rear wall, a heat transfer apparatus forming an element of said refrigerator, said apparatus comprising a continuous serpentine conduit formed to provide a plurality of parallel passes, a plurality of spaced parallel wires secured to said conduit and extending transversely of said passes, and means for mounting said heat transfer apparatus on said rear wall, said heat transfer apparatus including a central planar section parallel to said rear wall, and upper and lower planar sections inclined to said central section and to said rear wall.

5. A refrigerator comprising a cabinet including a vertical rear wall, a heat transfer apparatus forming an element of said refrigerator, said apparatus comprising a continuous serpentine conduit formed to provide a plurality of parallel passes, a plurality of spaced parallel wires secured to said conduit and extending transversely of said passes, and means for mounting said heat transfer apparatus on said rear wall, said heat transfer apparatus including a central planar section parallel to said rear wall and spaced therefrom, an upper planar section extending from said central section and inclined toward said rear wall, and a lower planar section extending from said central section and inclined toward said rear wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,699,542 Murray Jan. 22, 1929 1,884,096 Modine Oct. 25, 1932 1,942,432 Kimball et a1 Jan. 9, 1934 1,996,691 Tenney Apr. 2, 1935 2,105,751 Money Jan. 18, 1938 2,378,524 Yerkes June 19, 1945 2,469,635 Dalin May 10, 1949 FOREIGN PATENTS 457,376 Great Britain Nov. 26, 1936 

